For a projection device, a blue laser diode is generally adopted to provide a blue light to excite a phosphor on a phosphor wheel to generate a yellow light. Then, the required red light and green light are filtered out through a filter wheel, and are then accompanied with the blue light emitted by the blue laser diode to constitute the three primary colors, red, green and blue, required for projection pictures.
In a conventional architecture adopting a blue laser diode accompanied with a phosphor wheel, a dichroic element is provided between the blue laser diode and the phosphor wheel. The blue light passes through the dichroic element and is transmitted to the phosphor wheel. The yellow light generated by the phosphor is reflected to the dichroic element and is reflected by the dichroic element to the filter wheel. In addition, it is necessary to use a plurality of reflection mirrors so that the blue light, not absorbed by the phosphor, additionally winds around a circle of light paths and passes through the dichroic element to be transmitted to the filter wheel. Therefore, a volume of the conventional architecture adopting a blue laser diode accompanied with a phosphor wheel is relatively larger, resulting in the circumstance that a volume of the projection device cannot be reduced.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.